Re: [PATCH v5 1/2] Add ftruncate_file that truncates a struct file

[Christian Brauner <brauner@kernel.org>]

On Wed, Jan 24, 2024 at 10:33:00AM +0200, Tony Solomonik wrote:
> do_sys_ftruncate receives a file descriptor, fgets the struct file, and
> finally actually truncates the file.
> 
> ftruncate_file allows for passing in a file directly, with the caller
> already holding a reference to it.
> 
> Signed-off-by: Tony Solomonik <tony.solomonik@gmail.com>
> ---
>  fs/internal.h |  1 +
>  fs/open.c     | 53 +++++++++++++++++++++++++++------------------------
>  2 files changed, 29 insertions(+), 25 deletions(-)
> 
> diff --git a/fs/internal.h b/fs/internal.h
> index 58e43341aebf..78a641ebd16e 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -182,6 +182,7 @@ extern struct open_how build_open_how(int flags, umode_t mode);
>  extern int build_open_flags(const struct open_how *how, struct open_flags *op);
>  extern struct file *__close_fd_get_file(unsigned int fd);
>  
> +long ftruncate_file(struct file *file, loff_t length, int small);
>  long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
>  int chmod_common(const struct path *path, umode_t mode);
>  int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
> diff --git a/fs/open.c b/fs/open.c
> index 02dc608d40d8..649d38eecfe4 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -154,49 +154,52 @@ COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length
>  }
>  #endif
>  
> -long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
> +long ftruncate_file(struct file *file, loff_t length, int small)

All internal functions that io_uring currently calls are called do_*():

* do_rmdir()
* do_unlinkat()
* do_mkdirat()
* do_symlinkat()
* do_statx()

So I'd follow that pattern and just call that thing do_ftruncate().
Otherwise looks good to me,

Acked-by: Christian Brauner <brauner@kernel.org>